This invention relates to a scroll type fluid machine comprising a first scroll and a second scroll which performs a gyrating movement relative to the first scroll relatively.
JP 09-133087 A discloses a whole system rotation scroll type fluid machine in which scrolled wraps extend from a drive scroll end plate and a follower scroll end plate, respectively, and are engaged with each other. A drive scroll is gyrated relative to a follower scroll to make closed spaces formed by rotation of the both scrolls move from a peripheral side to an inner side so as to reduce volume of the closed spaces, and in which sucked fluid is compressed and discharged.
JP2004-286025 A by this inventor discloses a scroll type fluid machine which comprises a casing; a follower scroll unit which is constituted of at least an outer peripheral block held on the casing rotatably and a follower wrap extending spirally from the outer peripheral block inwardly; a drive scroll unit which comprises a drive wrap engaging with the follower wrap, a pair of end plates gripping and fixing the drive wrap and holding the follower wrap slidably and a drive shaft supporting the casing rotatably and eccentrically relative to the follower scroll unit in order to rotate the end plates and which defines compression spaces with the follower scroll unit; an intake opening formed in the outer peripheral block and communicating with the compression spaces; and a discharge opening formed in the drive shaft and communicating with the compression spaces.
A monograph (Japan machinery society (B adition) volume 54, No. 498 (S63-2), monograph No. 87-0436B “Study for Scroll Fan and Blower”) discloses that a fan or a blower is constituted by combining balance type bladed wheels in which two scrolls are used so that one of the wheels directly connects to a motor and another of the wheels is followed by a side wall of the scroll.
In the whole system rotation scroll type fluid machine disclosed in JP 09-133087 A, the follower scroll rotates with rotation of the drive scroll and gyrates relative to the drive scroll in order to reduce the volume of the closed spaces. However, because thrust load acts on the end plates in a direction pushing the end plates away from each other, there is a disadvantage in that a large load is applied to bearings. Besides, in the case that a volume of the closed space is increased in order to increase discharge volume, the scroll wraps have to be elevated, but in this case, since radial load is applied perpendicularly to an axis at a middle position of the wrap's height, a disadvantage arises in that an upsetting moment is increased in the case of the cantilever type arrangement as shown in JP 09-133087.
Thus, in JP 2004-286025 A, the inventor disclosed a scroll type fluid machine which can increase the volume of compression spaces because the thrust load is set off with strength of the drive scroll's wrap so as not to act as a thrust load to the bearings by means of providing a pair of end plates so as to grasp the both sides of the drive scroll's wrap and make the follower scroll's wrap rotatable between the both end plates, so that the volume of the compression space can be increased.
A scroll type fluid machine disclosed in the monograph is that: because two wraps with the same shape are used in a drive scroll side and a follower scroll side respectively and they are combined so that they are deviated by π/2 (90°), their end portions are deviated by π/2 (90°), so that there is a disadvantage such that parts without contributing to compression are arisen.
In the scroll type fluid machine disclosed in JP 2004-286025 A, it is possible to increase discharge ability by further increasing wrap's strength of the follower scroll. Besides, in the case of this machine, because the drive scroll and the follower scroll are rotated together, it is supposed that rotation balance can be increased and ability of the machine can be increased.